This invention relates to a folding exercise bike, more particularly to an exercise bike with a pedal driven transmission box permitting a rotating bush at its output shaft to drive a universal joint to pull a saddle supporter making forward and backward motion possible. Meanwhile, the universal joint pulls the handle to permit its inward and outward turning relative to the motion of the saddle, thus allowing the bike to have pedaling, front inclining and breast expanding exercise functions. Again, the main frame, handle supporter and saddle supporter are of a knock down type thus making packing, transport and warehousing easy to save space and cost.
The conventional exercise bike has a simple function for lower limb exercise and therefore, is less effective for body building. An improvement has been proposed to modify the simple function into a multiple one to include pedaling, breast expanding and arm exercise, such as the same applicant filed on Mar. 13, 1985 as per U.S. Ser. No. 711,142 "Two-Stage Exercise Bike". The complicated structure of such a bike has the defects such as more parts, higher cost, time-consuming assembly and maintenance, and more chance of mechanical trouble. Another defect of the conventional simple or multiple functional exercise bike is that the fixed structure needs expensive packing, transport and warehousing which incurs more expense and space requirement. Manufacturers have been making an effort to overcome such defects but without practical results.